This was last summer (2013), I got off the train on my way to meet a friend when I felt the hand (backside of a hand) brush my butt. I quickly turned around and looked right at the guy who actually jumped at my quick reaction and he tried to walk off as if nothing happened. I followed after him so I could take his picture, he ducked into a pizza place on the corner near the train stop and rushed out the front door.
I had already called my friend who rushed to meet me but the guy was long gone…I got a pic of him though (from behind).